chemical changes and electrolysis Flashcards
Gain of oxygen is (a) and the loss of oxygen is (b)
(a) oxidation
(b) reduction
Is the more reactive a metal is, the more easily it loses electrons?
Yes
What do metals that react with water give?
Metal hydroxide and hydrogen gas.
What do metals that react with a dilute acid give?
Metal salts and hydrogen gas.
More reactive metals will displace (a) reactive metals from solutions of metal (b)
(a) less
(b) salts
What is the phonetic method of remembering the reactive series?
PoSLiCaMZIC.
Where are metals from the Earth’s crust found?
In rocks called ores, they contain enough metal to make it worthwhile to use them.
These metals can be extracted using electrolysis because they are more reactive than carbon and their oxides are not reduced by heating with carbon.
Potassium, sodium, lithium, calcium, magnesium, aluminium.
These 3 metals are less reactive than carbon and therefore their oxides can be reduced to the metal by heating with carbon.
Zinc, iron, copper.
These metals are found uncombined and do not have to be extracted.
Gold and silver.
What is the reason acids have similar properties?
They all contain hydrogen and when in aqueous solution they all give hydrogen ions.
What acids react with metals to form salts and hydrogen?
Hydrochloric and sulfuric.
(a) are soluble metal hydroxides; bases are (b) metal oxides and hydroxides.
(a) Alkalis
_(b)_insoluble
acid + carbonate -> (a) + (b) + (c)
(a) salt
(b) water
(c) carbon dioxide
When is an aqueous solution formed?
When a substance dissolves in water.
In neutralisation, H+ and OH- react to give what?
Water.
A concentrated solution of an acid has a
(a) amount (in moles) of the acid dissolved in the same (b) of water than a (c) solution.
(a) greater
(b) volume
(c) dilute
A strong acid like hydrochloric acid is completely/partially ionised in aqueous solution. A weak acid like ethanoic acid is completely/partially ionised in aqueous solution.
completely
partially
True or false: Strong is the same as concentrated and weak is the same as dilute.
False.
What happens to the H+ ions if the pH value of a solution decreases by 1 unit.
They increase by 10 times or 1 order of magnitude.
Electrolysis is the (a) up of an ionic compound using (b). It takes place when the ionic compounds are in (c) state or in aqueous solution because the ions are (d) to move around.
(a) splitting
(b) electricity
(c) liquid
(d) free
What is the liquid decomposed by electrolysis called?
Electrolyte.
When ions lose or (a) electrons at the electrodes they are (b).
(a) gain
(b) discharged
Where do the negative ions move toward?
The positive electrode (anode) they lose electrons to form non- metallic elements.
Where do the positive ions move toward?
The negative electrode (cathode) they gain electrons to form metallic elements.
What are the reactions generally at the cathode? (half equation)
Mn+ + ne- = M
What are the reactions at the anode? (half equation)
2Xm- –> X2 + 2me-
What is used to extract aluminium?
The electrolyte used is aluminium oxide.
Aluminium has a (a) MP so to save energy and lower the operating temperature, the aluminium oxide is (b) in a compound called (c). (d) is used at both electrodes. Aluminium ions are (e) at the (f) to give molten aluminium metal which is run off. At the anode, (g) ions are discharged to form (h) gas. This oxygen gas then reacts with the carbon anode to form (i). The carbon anode burns away and loses mass.
(a) high
(b) dissolved
(c) cryolite
(d) carbon
(e) discharged
(f) cathode
(g) oxide
(h) oxygen
(i) carbon dioxide
What is produced when metal+oxygen react
metal oxides
What is the displacement order
a metal can only displace another metal from a compound if it is located above it in the reactivity series
What are spectator ions
unchanged in a reaction
How does potassium react with cold water
hydrogen produced ignites instantly, then the metal also ignites setting off a lilac flame
How does sodium react with cold water
fizzes rapidly, melts to form a ball which floats around surface
How does lithium react with cold water
fizzes and floats
What is a redox reaction
reaction with both reduction and oxidation
acid +metal oxides-> ?
salt+ water
acid + hydroxide -> ?
salt + water
how can u measure pH
universal indicator, pH probe
process by which carbon is used to extract metals from their oxides when the metal is less reactive than carbon
- metals can be extracted by reacting with carbon
- in reduction the metal oxide loses oxygen to form a pure metal
- reduction with carbon normally involves heating metal oxide in the presence of the carbon (often coal)
- carbon is used because it is cheap and abundant
metals that react with dilute acids but not cold water
magnesium aluminium zinc iron lead
metals that don’t react with dilute acids
platinum gold silver copper
what does the metal lose in a reduction reaction and form
oxygen, a pure metal
what metal does hydrochloride acid make
chloride
what metal does nitric acid make
nitrate
what metal does sulphuric acid make
sulphate
moles=…?
concentration x volume
in an aqueous solution, at the anode what is formed when halide ions are present
halogen
in an aqueous solution, at the anode what is formed when halide ions are absent
oxygen
in an aqueous solution, at the anode what is formed when halide ions are absent
oxygen
in an aqueous solution, at the cathode what is formed when the metal is more reactive than
hydrogen
in an aqueous solution, at the cathode what is formed when the metal is less reactive than hydrogen
metal
